/*********************************************************************
 * Copyright (C) 2002 Andrew Khan
 * <p>
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2.1 of the License, or (at your option) any later version.
 * <p>
 * This library is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * Lesser General Public License for more details.
 * <p>
 * You should have received a copy of the GNU Lesser General Public
 * License along with this library; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
 ***************************************************************************/

package jxl.write.biff;

import jxl.biff.IntegerHelper;
import jxl.biff.Type;
import jxl.biff.WritableRecordData;

/**
 * Index into the cell rows in an worksheet
 */
class IndexRecord extends WritableRecordData {
    /**
     * The binary data
     */
    private byte[] data;
    /**
     * The numbe of rows served by this index record
     */
    private int rows;
    /**
     * The position of the BOF record in the excel output stream
     */
    private int bofPosition;
    /**
     * The number of blocks needed to hold all the rows
     */
    private int blocks;

    /**
     * The position of the current 'pointer' within the byte array
     */
    private int dataPos;

    /**
     * Constructor
     *
     * @param pos the position of the BOF record
     * @param bl the number of blocks
     * @param r the number of rows
     */
    public IndexRecord(int pos, int r, int bl) {
        super(Type.INDEX);
        bofPosition = pos;
        rows = r;
        blocks = bl;

        // Allocate the amount of bytes required to hold all the blocks
        data = new byte[16 + 4 * blocks];
        dataPos = 16;
    }

    /**
     * Gets the binary data for output.  This writes out an empty data block, and
     * the information is filled in later on when the information becomes
     * available
     *
     * @return the binary data
     */
    protected byte[] getData() {
        IntegerHelper.getFourBytes(rows, data, 8);
        return data;
    }

    /**
     * Adds another index record into the array
     *
     * @param pos the position in the output file
     */
    void addBlockPosition(int pos) {
        IntegerHelper.getFourBytes(pos - bofPosition, data, dataPos);
        dataPos += 4;
    }

    /**
     * Sets the position of the data start.  This happens to be the position
     * of the DEFCOLWIDTH record
     */
    void setDataStartPosition(int pos) {
        IntegerHelper.getFourBytes(pos - bofPosition, data, 12);
    }
}
